ASH trees are a favourite nesting site for bluetits.

But one mixed-up bird in Durham City has opted to rear its young amid a pile of stubbed-out cigarette ends - in an ash tray.

Now smokers at St Aidan's College in Durham have been warned off using the container in case the bluetit - latin name parus caeruleus - develops a smoker's cough.

Maintenance staff were amazed to spot the bird flying into the metal grid of the cigarette box outside the college's main entrance.

On closer examination, they discovered that the creature had nested inside.

Maintenance manager Dennis Sharp said he could not understand why it had chosen the location.

"We've got lots of birds nests around but we've never had one in the ash tray," he said.

"The students think it's fantastic - the vast majority haven't had anything to do with wildlife, so as soon as we get anything like ducks on the pond, the girls get very protective. The guys are just as bad if not worse."

Mr Sharp said that he was unsure if there were eggs in the nest, but had put a notice up to remind the students not to use the container as a precaution. "It's exam time, so the bird's presence is taking a bit of the stress away," he added.

The bluetit, which numbers about 150,000 in Britain, normally selects holes in trees in which to nest. Its favourites are broad-leaved species such as oak and ash.